RT Journal Article SR Electronic T1 Interrupter resistance and oxygen saturation for methacholine challenge in young children JF ERJ Open Research JO erjor FD European Respiratory Society SP 00025-2015 DO 10.1183/23120541.00025-2015 VO 1 IS 2 A1 Nicole Beydon A1 Iulia Marian YR 2015 UL http://openres.ersjournals.com/content/1/2/00025-2015.abstract AB